1. Field
This invention relates generally to pressurized vessels, such as sterilizers. Specifically, this invention is directed to a class of sterilizers which are of modest size and have non-circular doors. The invention provides a clamping force which keeps the door in sealing relationship with the sterilizer in response to an increase in pressure differential across the door.
2. State of the Art
Sterilizers and similar pressurized vessels are well-known. Generally, sterilizers comprise an outer housing which contains a chamber. The chamber has an opening through which items are placed for sterilization. Associated apparatus and controls provide for the exposure of those items within the chamber to sterilants under sterilizing conditions, often at elevated pressure. It is common for a partial vacuum to exist within the chamber during a portion of an operating cycle. A door is attached to the outer housing, and is positioned to cover the chamber opening. Sterilizer doors are commonly designed to effect a pressure seal, using a resilient gasket which forms an interface between the door and the opening of the sterilizer chamber. Contact between the door and the gasket produces an initial seal of the chamber. Mechanical or pneumatic means may be arranged to either expand or compress the gasket, thereby to enhance the seal.
Sterilizers which are provided with round doors are efficiently sealed by latching mechanisms which do not work well with rectangular doors. Certain sterilizers are provided with doors having non-circular, e.g., rectangular shapes. The shape of the door is of less consequence to large capacity sterilizers, because they typically include massive structural means for securing the door in place against the gasket while the sterilizer is in operation. Such massive structures are not practical for use with the rectangular doors of sterilizers of moderate size, e.g. less than two cubic feet. The doors of these moderately sized sterilizers are typically provided with means such as sliding bolts and hook and latch devices.
Closure mechanisms currently used in association with doors provided for moderately sized sterilizers (e.g., sterilizers requiring doors having a width of from about six inches to about twelve inches) often fail to provide adequate sealing of the chamber during pressurization of the sterilizer. Further, door closure mechanisms currently in use with smaller sized sterilizers provide inadequate assurance that an even and competent seal between the chamber and the door will be maintained during pressurization of the sterilizer.
Thus, there remains a need for a closure mechanism capable of effecting an adequate and reliable seal for moderately sized pressure chambers or non-circular doors. There is also a need for such a mechanism which avoids the massive and complex structural arrangements currently in use with larger chambers.